Biomedical subjects

Gerhard Ziemer

Publications and source records attributed to Gerhard Ziemer.

36 records · Page 2Linked to original sources

PubMed2005

Glycoprotein IIb/IIIa inhibition reduces prothrombotic events under conditions of deep hypothermic circulatory arrest.

Deep Hypothermic Circulatory Arrest (DHCA) is employed during thoracic aortic and congenital heart surgery, and can induce postoperative neurological damage probably caused by microthrombembolism. Hypothermia has been reported to induce platelet activation and aggregation. The platelet activation marker P-selectin mediates binding of platelets to leukocytes. Tirofiban and eptifibatide, short-acting inhibitors of the platelet fibrinogen receptor GP IIb/IIIa, have recently been shown to protect platelet function without increasing bleeding during heart surgery using cardiopulmonary bypass. The aim of this study was to investigate the effect of tirofiban and eptifibatide on platelets and platelet-leukocyte interaction under DHCA conditions in vitro. Platelet aggregation, binding of the GP IIb/IIIa activation specific antibody PAC-1, P-selectin expression as well as monocyte and granulocyte content of aggregates were investigated in unstimulated and ADP-stimulated samples using flow cytometry. Tirofiban and eptifibatide inhibited massive platelet aggregation and PAC-1 binding which were induced by DHCA conditions. P-selectin expression was inhibited by tirofiban but increased by eptifibatide at hypothermia. Platelet-bound leukocytes were present in all samples. Eptifibatide increased granulocyte content of aggregates at hypothermia in ADP-stimulated samples. We conclude that under conditions of DHCA both tirofiban and eptifibatide inhibit platelet aggregation but have different effects on platelet P-selectin expression and platelet-leukocyte interaction. Application of a short-acting and non-activating GP IIb/IIIa inhibitor should be considered during DHCA in vivo to prevent occlusion of the microvasculature and subsequent organ damage.

Anticoagulants↗

PubMed2005

PVC-plasticizer DEHP in medical products: do thin coatings really reduce DEHP leaching into blood?

The hemocompatibility of artificial surfaces in extracorporeal blood circulation systems can be improved by coatings. According to the literature, heparin coatings should avoid the leaching of the plasticizer di(2-ethylhexyl) phthalate (DEHP) into the blood from components made from plasticized polyvinyl chloride (PVC). DEHP and its metabolites are known to impair the fertility of male rodents; effects on human fertility are assumed. Three different surface coatings with and without heparin were examined in a Chandler Loop model at 37 degrees C using fresh human blood to evaluate their hemocompatibility and barrier property to plasticizer. The levels of toxic oxidation products of DEHP generated in the blood, particularly, were found as high as in the uncoated tubing. The coatings improved the hemocompatibility, but are not safe protection against the hazardous metabolites of DEHP. For pregnant women, neonates and children, we would recommend using the available surface-coated plasticized PVC tubing sets, but free of DEHP.

Anticoagulants↗

PubMed2004

Emergency donor heart protection: application of the port access catheter technique using a pig heart transplantation model.

BACKGROUND: Organ shortage limits the number of transplantations, and donor deterioration may precede and often prevent conventional organ preservation. This study evaluates in situ perfusion as a bedside method for cardiac allograft procurement in a large animal model. METHODS: Thirty Landrace pigs (42 +/- 7 kg) were studied. The hearts in the conventional group underwent cardioplegic arrest with University of Wisconsin solution and sodium-hydrogen exchange inhibitor cariporide as an additive; they were explanted and stored on ice before transplantation. In the in situ group, one catheter was placed in the ascending aorta and another in the right atrium. After disconnection from the ventilator, hypoxia caused circulatory arrest. The aorta was endoclamped, and in situ perfusion of the aortic root was maintained with University of Wisconsin solution and cariporide. After explantation, hearts were stored on ice for 120 min. All hearts were implanted according to the Shumway technique. Ventricular pressure and cardiac output were monitored online, and troponin-I was measured intermittently. Two hours after weaning from extracorporal circulation, the animals were killed and histology was performed. RESULTS: Catheters were placed through introducers within 5 min. Functional recovery and histology were comparable between the two techniques. Troponin-I increased in both groups during reperfusion but at a faster rate in the in situ technique (P <0.01). CONCLUSION: In situ perfusion may be suitable for cardiac transplants when donor deterioration requires urgent organ preservation. Catheters can be placed at bedside and modified to achieve multi-organ protection through additional perfusion of the abdominal aorta.

Adenosine↗

PubMed2004

[Atrial isomerism and visceral heterotaxy].

Atrial isomerism and visceral heterotaxy describe complex pathoanatomic findings with defects in the determination of lateralization. Differentiation of right and left atrial isomerism was based on the anatomy of the atrial appendages and bronchial tree and often associated with asplenia in right atrial isomerism and polysplenia in left atrial isomerism. In these pa tients complex cardiac anomalies determine clinical symptoms and diagnostic procedures. At primary diagnosis in the neonatal period, systemic venous and pulmonary venous connections and intracardiac anatomy are identified using the sequential segmental approach. Therapeutic decisions and palliative procedures can usually be based on these initial echocardiographic findings. As many of the patients were found to have a functionally univentricular heart, surgical procedures following the Fontan principle (lateral tunnel or extracardiac conduit procedure) were introduced in patients with heterotaxy syndrome and successfully performed. Early survival and long-term outcome vary depending on associated cardiac and systemic and pulmonary venous anomalies. The therapeutic options and mid-term results in patients with heterotaxy syndrome undergoing the Fontan procedure are reported.

Abnormalities, Multiple↗

PubMed2004

Extracorporeal circulation without external clamping and cannulation of the aorta: transventricular placement of a new multifunctional aortic cannula.

BACKGROUND: Stroke is a devastating outcome of coronary artery bypass grafting (CABG). An atherosclerotic ascending aorta is a major risk factor for plaque detachment during cannulation and external clamping in patients undergoing CABG while on extracorporeal circulation (ECC). To avoid external cannulation and clamping we developed and tested a new multifunctional cannula in a pig model. METHODS: The cannula has a double-balloon endoclamping function and is placed via the apex of the left ventricle through the aortic valve in the ascending aorta. It has 2 integrated lines for cardioplegic solution and for venting the left ventricle. In this animal model, a single balloon cannula was used because of the short ascending aorta in pigs. RESULTS: The cannula was placed smoothly and reproducibly with a guide-wire technique. The cardioplegic solution was administered via aortic root perfusion. Weaning from ECC was uneventful, and macroscopic examination did not reveal any damage to the aortic valve. CONCLUSIONS: This cannula could be used in patients with a severe atherosclerotic ascending aorta. The risk of plaque detachment and stroke during ECC might be reduced.

Animals↗

PubMed2003

Sodium-hydrogen inhibitor cariporide (HOE 642) improves in situ protection of hearts from non-heart-beating donors.

BACKGROUND: Reperfusion injury is a vital problem in non-heart-beating donor (NHBD) organs. The sodium-hydrogen inhibitor cariporide is thought to improve cellular integrity after ischemia and reperfusion. Recently, we demonstrated the possibility of preserving hearts with in situ perfusion after circulatory death. The purpose of this study was to determine whether cariporide improves in situ heart protection. METHODS: We studied 20 pigs (18 +/- 2 kg). Hearts in the conventional group (CON, n = 6) underwent cardioplegic arrest with University of Wisconsin solution and then were explanted and stored for 150 minutes on ice. In the other groups, a catheter was placed in each ascending aorta and right atrium. After disconnecting the ventilator, hypoxia caused circulatory arrest within 7 +/- 2 minutes. The aorta was endoclamped, and continuous in situ perfusion of the aortic root was maintained for 60 minutes with University of Wisconsin solution (UW, n = 7) or with UW solution and cariporide (CAR, n = 7). After explantation, the hearts were stored on ice for 90 minutes. In all groups, hearts were reperfused with homologous, whole pig blood in an isolated working heart model for 45 minutes. We monitored stroke-work index on-line, intermittently measured troponin I and malondialdehyde, and compared light microscopic examinations among the groups. RESULTS: Stroke-work index was higher in the CAR group compared with the UW group during the last 20 minutes of reperfusion (10(3)dynes x cm x beats(-1)x gm(-1), 6.6 +/- 1.4 vs 4.5 +/- 2.0, p < 0.05), troponin I was lower in the CAR group compared with the UW group (161 +/- 32 ng/ml vs 277 +/- 35 ng/ml, p < 0.05). Results of malondialdehyde and light microscopic examinations were slightly better in the CAR group, without reaching statistical significance. CONCLUSION: Cariporide as an additive to UW solution improves functional recovery and decreases myocardial damage in hearts from NHBDs protected with an in situ perfusion technique.

Adenosine↗

PubMed2003

DDD pacemaker implantation after Fontan-type operations.

Bradyarrhythmias developing after Fontan-type operations impair the function of the univentricular heart causing fatigue, headaches, ascites, and protein-losing enteropathy (PLE). Transvenous inaccessibility, requiring epicardial implantation, accounts for the reluctance to implant a pacemaker (PM). Between 1997 and 2000, 24 patients (mean age 9.5 years, range 6 months to 19 years) with Fontan-type operations received DDD pacing systems with atrial steroid-eluting stitch-on electrodes (mean capture threshold 1.9 V/0.5 ms, range 0.4-3.5 V) and ventricular screw-in electrodes (mean capture threshold 1.7 V/0.5 ms, range 0.1-3 V). The systems were implanted at the time of conversion from atrio- to cavopulmonary connections in 5 patients, at the time of a total cavopulmonary Fontan operation in 6, and 1-50 months thereafter (mean = 18) in 13 patients. A right ventricular anatomy was present in 13 (54%) of 24 of PM recipients, versus 35% of the overall population. After a mean follow-up of 3.5 years, the PM were functioning in DDD mode in 23 of the 24 patients. Length of hospital stay in the ten patients who underwent repeat sternotomy was 5 days, without procedure related complications. In three children a repeat sternotomy was avoided by implanting the atrial electrodes during the Fontan operation. All patients improved clinically, including resolution of PLE in four patients. Bradyarrhythmias may lead to significant morbidity after Fontan-type operations. Electrophysiological evaluation is advised at follow-up. The indication for implantation of a DDD pacemaker system should be liberal. Placing atrial electrodes during the Fontan operation, especially in the presence of a right ventricular anatomy, avoids repeat sternotomy.

Adolescent↗

PubMed2003

Material-dependent levels of heat-shock protein 70 (hsp70) in human plasma following contact of blood with artificial surfaces.

Recently, it has been shown that heat-shock protein 70 (hsp70) functions in a dual role as a chaperone and a cytokine. However, no information is available on the occurrence of hsp70 in the extracellular milieu or on its ability to modulate cellular immune response. This study shows a material-dependent increase of hsp70 levels in plasma following contact of fresh heparinized whole human blood with three different biomaterials (PVC, heparin-coated PVC, Silicone). We report a previously unknown behavior of hsp70 to act as a plasma-adsorption protein. Further, high binding capacities for hsp70 to artificial surfaces (measured by Western blotting) and elevated hsp70 levels in plasma (measured by EIA) following contact with blood correspond with a reduced hemocompatibility. The degree of surface-induced activation of blood was determined by analysis of markers for coagulation, inflammation and complement activation. These findings indicate that the selective adsorption of hsp70 on artificial surfaces and the increased hsp70 levels in plasma may be important in directing host inflammatory and immune responses. We suggest that the levels of hsp70 in human plasma may represent a new prognostic factor or a diagnostic biomarker in hemostasis research.

Adsorption↗

PubMed2002

Sirolimus-eluting stents for the treatment of obstructive superficial femoral artery disease: six-month results.

BACKGROUND: Stent implantation for obstructive femoropopliteal artery disease has been associated with poor long-term outcomes. This study evaluated the effectiveness of shape memory alloy recoverable technology (SMART) nitinol self-expanding stents coated with a polymer impregnated with sirolimus (rapamycin) versus uncoated SMART stents in superficial femoral artery obstructions. METHODS AND RESULTS: Thirty-six patients were recruited for this double-blind, randomized, prospective trial. All patients had chronic limb ischemia and femoral artery occlusions (57%) or stenoses (average lesion length, 85+/-57 mm). Patients were eligible for randomization after successful guidewire passage across the lesion. Eighteen patients received sirolimus-eluting SMART stents and 18 patients received uncoated SMART stents. The primary end point of the study was the in-stent mean percent diameter stenosis, as measured by quantitative angiography at 6 months. The in-stent mean percent diameter stenosis was 22.6% in the sirolimus-eluting stent group versus 30.9% in the uncoated stent group (P=0.294). The in-stent mean lumen diameter was significantly larger in the sirolimus-eluting stent group (4.95 mm versus 4.31 mm in the uncoated stent group; P=0.047). No serious adverse events (death or prolonged hospitalization) were reported. CONCLUSIONS: The use of sirolimus-eluting SMART stents for superficial femoral artery occlusion is feasible, with a trend toward reducing late loss compared with uncoated stents. The coated stent also proved to be safe and was not associated with any serious adverse events.

Aged↗

PubMed2002

Occlusion versus shunting during MIDCAB: effects on left ventricular function and quality of anastomosis.

BACKGROUND: Minimally invasive direct coronary artery bypass is an established clinical procedure for revascularization of the left anterior descending coronary artery. Mechanical stabilization and temporary occlusion is currently used to perform the anastomosis of the internal thoracic artery to the left anterior descending coronary artery. However, critical reduction of cardiac function can occur as a result of temporary ischemia. The purpose of this study was to evaluate whether ischemic sequelae can be avoided by using temporary intraluminal shunts and whether this alters early outcome. METHODS: Thirty-five patients underwent minimally invasive direct coronary artery bypass revascularization using a mechanical stabilizer. In group A (n = 20), the anastomotic site was temporarily occluded by tourniquets. In group B (n = 15), temporary intraluminal shunts were inserted into the anastomotic site without any occlusion of the left anterior descending coronary artery. Anastomosis of the internal thoracic artery to the left anterior descending coronary artery was performed in an identical fashion. A Swan-Ganz catheter was inserted, and transesophageal echocardiographic measurements were obtained for analysis of left ventricular (LV) function. Regional wall motion, cardiac index, stroke volume index, systolic and diastolic LV diameters, and fractional area change were measured during four periods: at the start of the operation (baseline), placement of the stabilizer (stabilization), left anterior descending coronary artery occlusion (occlusion) or insertion of temporary intraluminal shunts (shunt), and 30 minutes after reperfusion (reperfusion). Angiograms were obtained 4 to 6 days postoperatively. RESULTS: In group A, LV performance, cardiac index, stroke volume index, and fractional area change decreased during occlusion whereas systolic diameters increased. Almost two myocardial segments per patient developed severe hypokinesia in the perfusion area. These changes disappeared after 30 minutes of reperfusion, with increased LV function. In group B, LV function remained stable whereas hypokinetic wall motion was only detected in 2 patients. Early angiograms revealed 90% of the grafts were patent in group A versus 100% in group B. The need for percutaneous intervention during the first 6 months was 20% in group A versus 6.7% in group B. CONCLUSIONS: The use of temporary intraluminal shunts resulted in reduced acute ischemia and revealed wall motion abnormalities and maintained LV function. Furthermore, this technique suggests an improvement of early graft patency and a lower reintervention rate within the first 6 postoperative months. Thus, use of temporary intraluminal shunts appears to be superior to the occlusion technique early after minimally invasive direct coronary artery bypass procedures.

Aged↗

PubMed2002

Fontan-type procedures: residual lesions and late interventions.

BACKGROUND: The purpose of this study was to determine the type and incidence of hemodynamic and electrophysiological abnormalities requiring surgical or catheter-based interventions in a single-center long-term experience. METHODS: Eighty-eight patients with a follow-up of at least 5 years (mean follow-up, 9.6 +/- 2.6 years) after Fontan-type procedures were included. All patients had undergone cardiac catheterization either as part of the regular postoperative protocol or because of symptomatic atrial tachycardia or increasing cyanosis. RESULTS: Freedom from reoperation for up to 5 years was documented for 82% of patients and decreased to 76% after 8 years. Late reoperations included conversion of an atriopulmonary anastomosis to a total cavopulmonary anastomosis in 2 patients with atrial dysrhythmia and implantation of an extracardiac conduit in 1 patient with left atrial isomerism and intrapulmonary arteriovenous malformations after a Kawashima operation. Decline in sinus node function with symptomatic bradycardia required pacemaker therapy in 10 patients (11%). Transcatheter interventions included fenestration occlusion in 5 of the 11 patients with initial baffle fenestration. In 6 of 17 patients with aortopulmonary collaterals, coil occlusion was indicated to reduce future systemic ventricular volume load. Various systemic venous collaterals were documented in 11 patients and required coil occlusion in 2. One patient with symptomatic protein-losing enteropathy underwent transcatheter fenestration creation without sustained relief of symptoms. Freedom from transcatheter interventions decreased from 94% to 82% after 5 and 10 years, respectively. CONCLUSIONS: During long-term follow-up, reoperations are rare and mainly involve Fontan conversion to either a lateral-tunnel or extracardiac-conduit procedure. Detailed angiographic evaluation on a routine basis allows identification of the vascular sites of origin of aortopulmonary collateral vessels and systemic venous collaterals potentially developing during long-term follow-up. Transcatheter interventions including fenestration occlusion and occlusion of venous collaterals and aortopulmonary collaterals were performed to maintain and improve the Fontan circulation in clinically symptomatic and asymptomatic patients. During long-term follow-up after Fontan-type operations, a regular postoperative cardiac catheterization protocol is recommended.

Adolescent↗

PubMed2002

Hemocompatibility of heparin-coated surfaces and the role of selective plasma protein adsorption.

Although several studies have shown that heparin-coated surfaces reduce the activation of both the complement system and the coagulation system, there is still inadequate understanding of the factors initiating and controlling blood activation at these surfaces. We investigated the adsorption profile of 12 common plasma proteins (and the platelet receptor CD41) to a heparin coating (Carmeda BioActive surface (CBAS)) compared to uncoated controls (PVC) by using an in vitro whole blood Chandler-Loop model. Surface bound proteins were studied kinetically by a direct ELISA technique. Western blots were performed on the SDS eluates in order to detect adsorbed cleavage products and denatured proteins. Changes in plasma levels of neutrophil activation markers, platelet activation, coagulation activation, complement activation and the inflammatory response were measured by conventional ELISAs. This study showed significant differences in adsorption patterns among the heparin-coated and the uncoated surfaces, notably for fibronectin, fibrinogen, C3 and high molecular weight kininogen (HMWK). The kinetic studies confirmed the results obtained from Western blots and indicated specific adsorption profiles of plasma proteins. We assume that at least some of the improved blood compatibility of the heparin-coated surfaces may be ascribed to the selective uptake and cleavage of plasma proteins.

Adsorption↗

PubMed2002

Hemocompatibility of medical connectors with biopassive or bioactive surface coatings.

Although medical connectors compose very small parts of the extracorporeal circulation (ECC) system they represent a critical localization where early thromboembolic processes can manifest. In the present study we modified an in vitro closed-loop model with fresh human whole blood for the preclinical evaluation of the hemocompatibility of three types of medical connectors: non-coated (control); with silicone-, and heparin-coating. Each single loop consists of five polycarbonate connectors joined together by five pieces of silicone tubes. Thrombin-antithrombin-III, beta-thromboglobulin (beta-TG), PMN-Elastase, terminal complement complex, CD 11b expression, and surface-absorbed fibrinogen were measured. After 1 and 2 h recirculation, platelet loss, release of beta-TG, and adsorption of fibrinogen were significantly higher (p<0.05) within the non-coated connectors compared to the silicone- and heparin-coated groups. Following this experiment, the connectors were filled again with fresh heparinized whole blood from the same donor to evaluate the influence of prior blood contact. Here, the activation of platelets and coagulation was dependent on the duration of the blood preincubation period. Probably, the coated surfaces possess a reduced, or selective adsorption of plasma proteins, which in turn leads to a faster creation of a blood-friendly secondary superficial membrane, and prevents a further denaturation and hence activation of the adsorbed proteins.

Adsorption↗

PubMed2002

Economic value of thrombolysis with adjunctive abciximab in patients with subacute peripheral arterial occlusion.

BACKGROUND AND OBJECTIVE: Glycoprotein (GP) IIb/IIIa receptor inhibitors enhance thrombolysis in patients with acute coronary syndromes. This analysis evaluates the economic impact of abciximab, a GP IIb/IIIa inhibitor, as an adjunct to urokinase in peripheral artery occlusions of less than 6 weeks duration. STUDY DESIGN: A post-hoc economic analysis was performed using clinical data and inpatient resource utilisation derived from the prospective comparative phase II Platelet Receptor Antibodies in Order to Manage Peripheral Artery Thrombosis (PROMPT) pilot study. Study endpoints were amputation-free survival and survival without open surgery or major amputation after 90 days, and the rate of major complications at 30 days. PERSPECTIVE: Third-party payer and the societal perspective. PATIENTS AND METHODS: Seventy patients with lower extremity thrombi were randomised (2 : 5 ratio) to urokinase plus placebo or to urokinase plus abciximab. Economically relevant data were retrospectively derived from the clinical study database from a specific evaluation of patient records and from expert opinion. RESULTS: From the viewpoint of the society, average total per-patient direct and indirect costs accruing over 3 months were more favourable for treatment with abciximab plus urokinase than for urokinase alone [9723 euros (EUR) vs EUR10 322; 2000 values], despite higher initial hospitalisation costs of the combination therapy. Abciximab plus urokinase was the dominant strategy at 3 months due to a clinically higher rate of survival without amputation or bypass surgery coupled with a lower average per-patient cost. From the perspective of the third-party payer, treatment with abciximab plus urokinase was economically also superior to urokinase alone (EUR8773 vs EUR9663). CONCLUSIONS: Based on the preliminary findings of the PROMPT trial, the use of abciximab as an adjunct to urokinase in patients with subacute peripheral artery occlusions may be the favourable strategy compared with urokinase alone, in terms of clinical and economic outcomes. Further trials are needed to confirm these clinical and economic findings. The preliminary clinical benefits experienced by patients treated with abciximab plus urokinase in the PROMPT trial translated into cost savings in terms of reduced direct medical costs at 3 months. These cost savings more than offset the cost of abciximab. The use of abciximab as an adjunct to urokinase in patients with subacute peripheral artery occlusions may be the favourable strategy compared with urokinase-alone in terms of clinical and economic outcomes, but further trials are needed to confirm the these clinical and economic findings.

Abciximab↗

PubMedDate not supplied

Treatment of periprosthetic soft tissue infection of the groin following vascular surgical procedures by means of a polyvinyl alcohol-vacuum sponge system.

Deep groin infections after prosthetic vascular surgical procedures represent a serious complication of surgical practice. Septicemia and/or erosive hemorrhage can both be consequences. In this situation, removal of the graft appears to be the only option. However, if the infection is detected early (type Szilagyi III), local treatment to eradicate the infection could serve as an alternative. Twenty-four patients with confirmed infection of the soft tissue adjacent to the prosthetic material in the groin were treated locally by implantation of a vacuum sponge system. Duration of this treatment was 2 weeks. All patients showed excellent tissue granulation of the wound area and the microbial stains were negative at the end of therapy. In 21 patients the wound could be primarily closed after explantation of the sponge. Three patients underwent open treatment because of a skin defect. After 12 months, the wounds had healed well in all patients. Histologic evaluation revealed a physiological healing process. Deep soft tissue infections of the groin adjacent to prosthetic vascular material (type Szilagyi III) can be treated effectively and safely with the vacuum sponge system. The treatment is inexpensive, easy to perform, and the initial vascular reconstruction can be preserved.

Aged↗

PubMedDate not supplied

A non-heart-beating donor model to evaluate functional and morphologic outcomes in resuscitated pig hearts.

A non-heart-beating donor model was considered to examine whether pig hearts from the abattoir could be resuscitated by whole blood reperfusion. For preservation, machine perfusion using University of Wisconsin (UW) solution was compared with storage on ice. Nineteen hearts from abattoir pigs, harvested 25 +/- 3 min after exsanguination, were harvested and transported to the laboratory. Controls (n = 7) were immediately reperfused with homologous whole pig blood in an isolated heart model for 60 min with monitoring of left ventricular developed pressure (LVDP), contractility, and coronary flow. UW solution hearts (UW, n = 6) were perfused for 4 h with 10 degrees C cold UW solution before blood reperfusion. In the cold storage group (CS, n = 6), the organs were stored for an additional 4 h on ice before blood reperfusion. In all hearts, histology was performed after 60 min of blood reperfusion to evaluate myocardial reperfusion injury. All three groups showed significant increases in LVDP (p <.001), although this functional recovery was earliest in the control group and latest in the UW group. Significant declines were observed for both LVDP and contractility from the peak values in each group to the end of blood reperfusion. Coronary flow increased steadily over the time course for the UW group, whereas in the control and CS groups flow increased during the first 15 min of blood reperfusion and then decreased. In the UW and CS groups, there were significant positive correlations between coronary flow and LVDP (p <.001). Microscopic examination revealed no differences between the three groups. Thus, hearts from an abattoir with 25 min of warm ischemic time can be resuscitated. For storage of these organs, continuous machine perfusion with UW solution is superior to cold storage on ice.

Adenosine↗

PubMedDate not supplied

Hemocompatibility of PMEA coated oxygenators used for extracorporeal circulation procedures.

An inflammatory response to cardiopulmonary bypass (CPB) caused by bioincompatibility of extracorporeal circuits is one of the major clinical issues in cardiac surgery. Recently a new coating material, poly-2-methoxyethylacrylate (PMEA), was developed to improve the biocompatibility of blood contacting surfaces. In a simulated cardiopulmonary bypass model, using fresh human whole blood, 15 membrane oxygenators (Capiox SX18, Terumo Corp., Tokyo, Japan) were compared. Five of them had the PMEA coating, five had a heparin-coated surface, and five had no surface treatment. Blood samples were taken at several time-points during a 90 minute circulation period. Changes in coagulation, complement, and blood cell alteration factors were measured by ELISA methods, plasma bradykinin levels were measured by radioimmunoassay, and expression of genes encoding cytokines TNF-alpha, interleukin-1beta, interleukin-6, and interleukin-8 was determined by semiquantitative real time RT-PCR. Platelet adhesion was significantly reduced in both the PMEA and the heparin coated circuits. Release of platelet activation marker beta-thromboglobulin was significantly higher in the uncoated control group (p < 0.01). After 5 minutes of blood circulation bradykinin levels significantly increased in all three groups (p < 0.01); however, the group with the PMEA coated oxygenators showed the lowest values. Expression of genes encoding proinflammatory cytokines in monocytes was increased in all groups, with the lowest being in the PMEA coated group. PMEA coated CPB surfaces in an in vitro experimental model showed an improved thrombogenicity, reduced bradykinin release, less platelet activation and less proinflammatory cytokines gene expression in comparison with a noncoated group. The authors assume that PMEA coating may ameliorate some of intra- and postperfusion syndromes, particularly hypotension, unspecific inflammation, hyperfibrinolysis, and blood loss.

Acrylates↗

PubMedDate not supplied

Aptamer-based capture molecules as a novel coating strategy to promote cell adhesion.

The improvement of the cytocompatibility of medical implants is a major goal in biomaterials research. During the last years many researchers worked on the fascinating approach to seed the respective cell types on various artificial substrates before implantation. For instance, cell-seeded implants are supposed to be better candidates for transplantable bone substitutes than conventional artificial bone grafts. To improve cell seeding efficiency and cytocompatibility, we designed a new coating material for medical implants. We used aptamers, highly specific cell binding nucleic acids generated by combinatorial chemistry with an in vitro selection called systematic evolution of exponential enrichment (SELEX). Aptamers do have high binding affinity and selectivity to their target. In our study, human osteoblasts from osteosarcoma tissue were used as a target to create the aptamer. Single aptamer mediated cell sorting assays showed the binding affinity with osteoblasts. Additionally, the aptamers immobilized on tissue culture plates could capture osteoblasts directly and rapidly from the cell solution. This model proves that aptamer coated artificial surfaces can greatly enhance cell adhesion. We assume that this strategy is capable to improve the clinical application of tissue engineered implants.

Base Sequence↗